Shedding from the vaccinated

The spike protein is only dangerous when expressed by your cells, which requires the mRNA programming.
It's really a question of the Adeno-associated virus (AAV) viral vector that they use. 80 Percent of the adult population already have antibodies to (natural) AAV, and there are many types of them. I think they use AAV2 for most gene therapy in humans. So if the mRNA is to enter human cells, you must be infected with the AAV virus that they use in the vaccine. (carrying the mRNA payload)

But since they use very small amounts I don't think it's likely. What's more concerning is the potential of vertical transmission, (mother to child) or maybe even genetic changes in human populations is the long run, so that you can inherit these genetic alterations.
I think this seems to be the most likely correct answer when you take into account all cause mortality rates as well. All cause mortality hasn't raised at all in unvaccinated populations. Yet it has sky rocketed in the vaccinated. Likewise when you break it down into groups like cardiac deaths or blood clots. No increase in cardiac deaths for the unvaccinated, yet a large increase for the vaccinated. Whatever is causing the main damage (which I think you're correct, is the mRNA payload and resulting spike protein expression), isn't being transmitted to the unvaccinated. Whatever is being shed and transmitted is obviously not good as it's causing the side effects and sickness people are talking about. But it seems like if you havn't been injected with the mRNA payload then it's something your immune system will fight off.

New Evidence Suggests mRNA COVID-19 Vaccine Transmission of Aerosols by Vaccinated to Unvaccinated

New evidence suggests vaccinated individuals can transmit antibodies generated through mRNA COVID-19 vaccination to unvaccinated individuals through aerosols, according to a peer-reviewed study published in ImmunoHorizons.

Extended mask requirements allowed scientists at the University of Colorado to evaluate whether vaccinated individuals could transfer aerosolized antibodies generated from COVID-19 vaccines. Aerosols are a manufactured or naturally occurring suspension of particles or droplets in the air, such as airborne dust, mists, fumes, or smoke, that can be absorbed by the skin or inhaled.

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